This proposal is to request support for a Keystone meeting entitled ?Mast Cells,[unreadable] Basophils, and IgE: Host Defense and Disease?, which will be held in Copper Mountain[unreadable] from January 20-24, 2007. Mast cells, basophils, and IgE form a strongly conserved[unreadable] interface between innate and adaptive mucosal immune systems. Each cell is a[unreadable] sensitive detector of environmental perturbations, to which they respond by generating[unreadable] and releasing a distinctive profile of mediators. The development of progressively more[unreadable] sophisticated experimental models has permitted the recognition of clear-cut and novel[unreadable] functions for mast cells and basophils in mediating effector cell recruitment, facilitating[unreadable] antigen presentation, inducing and amplifying immune responses, and modulating host[unreadable] responses in disease models. This program will focus on new aspects of cell[unreadable] development and trafficking of both lineages, homeostatic controls of cell activation, indepth[unreadable] examination of mast cell and basophil-derived mediators, the roles of these cells[unreadable] in both allergic (IgE-mediated) and non-allergic disease, and therapeutic modulation of[unreadable] their roles in both mouse models and human disease.